The abstract base class for all 'terminal' processing blocks.A signal processing flow is constructed by creating a tree of hierarchical blocks, which at any level may also contain terminal nodes that actually implement signal processing functions. This is the base class for all such leaf nodes. More...
#include <gr_block.h>
Public Types | |
| enum | { WORK_CALLED_PRODUCE = -2, WORK_DONE = -1 } |
| Magic return values from general_work. More... | |
Public Member Functions | |
| virtual | ~gr_block () |
| unsigned | history () const |
| void | set_history (unsigned history) |
| bool | fixed_rate () const |
| Return true if this block has a fixed input to output rate. | |
| virtual void | forecast (int noutput_items, gr_vector_int &ninput_items_required) |
| Estimate input requirements given output request. | |
| virtual int | general_work (int noutput_items, gr_vector_int &ninput_items, gr_vector_const_void_star &input_items, gr_vector_void_star &output_items)=0 |
| compute output items from input items | |
| virtual bool | start () |
| Called to enable drivers, etc for i/o devices. | |
| virtual bool | stop () |
| Called to disable drivers, etc for i/o devices. | |
| void | set_output_multiple (int multiple) |
| Constrain the noutput_items argument passed to forecast and general_work. | |
| int | output_multiple () const |
| void | consume (int which_input, int how_many_items) |
Tell the scheduler how_many_items of input stream which_input were consumed. | |
| void | consume_each (int how_many_items) |
Tell the scheduler how_many_items were consumed on each input stream. | |
| void | produce (int which_output, int how_many_items) |
Tell the scheduler how_many_items were produced on output stream which_output. | |
| void | set_relative_rate (double relative_rate) |
| Set the approximate output rate / input rate. | |
| double | relative_rate () const |
| return the approximate output rate / input rate | |
| virtual int | fixed_rate_ninput_to_noutput (int ninput) |
| Given ninput samples, return number of output samples that will be produced. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this. | |
| virtual int | fixed_rate_noutput_to_ninput (int noutput) |
| Given noutput samples, return number of input samples required to produce noutput. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this. | |
| gr_block_detail_sptr | detail () const |
| void | set_detail (gr_block_detail_sptr detail) |
Protected Member Functions | |
| gr_block (const std::string &name, gr_io_signature_sptr input_signature, gr_io_signature_sptr output_signature) | |
| void | set_fixed_rate (bool fixed_rate) |
Detailed Description
The abstract base class for all 'terminal' processing blocks.
A signal processing flow is constructed by creating a tree of hierarchical blocks, which at any level may also contain terminal nodes that actually implement signal processing functions. This is the base class for all such leaf nodes.
Blocks have a set of input streams and output streams. The input_signature and output_signature define the number of input streams and output streams respectively, and the type of the data items in each stream.
Although blocks may consume data on each input stream at a different rate, all outputs streams must produce data at the same rate. That rate may be different from any of the input rates.
User derived blocks override two methods, forecast and general_work, to implement their signal processing behavior. forecast is called by the system scheduler to determine how many items are required on each input stream in order to produce a given number of output items.
general_work is called to perform the signal processing in the block. It reads the input items and writes the output items.
Member Enumeration Documentation
Constructor & Destructor Documentation
| virtual gr_block::~gr_block | ( | ) | [virtual] |
| gr_block::gr_block | ( | const std::string & | name, |
| gr_io_signature_sptr | input_signature, | ||
| gr_io_signature_sptr | output_signature | ||
| ) | [protected] |
Member Function Documentation
| void gr_block::consume | ( | int | which_input, |
| int | how_many_items | ||
| ) |
Tell the scheduler how_many_items of input stream which_input were consumed.
| void gr_block::consume_each | ( | int | how_many_items | ) |
Tell the scheduler how_many_items were consumed on each input stream.
| gr_block_detail_sptr gr_block::detail | ( | ) | const [inline] |
Referenced by set_detail().
| bool gr_block::fixed_rate | ( | ) | const [inline] |
Return true if this block has a fixed input to output rate.
If true, then fixed_rate_in_to_out and fixed_rate_out_to_in may be called.
Referenced by set_fixed_rate().
| virtual int gr_block::fixed_rate_ninput_to_noutput | ( | int | ninput | ) | [virtual] |
Given ninput samples, return number of output samples that will be produced. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this.
Reimplemented in gr_test, gr_sync_block, gr_sync_decimator, and gr_sync_interpolator.
| virtual int gr_block::fixed_rate_noutput_to_ninput | ( | int | noutput | ) | [virtual] |
Given noutput samples, return number of input samples required to produce noutput. N.B. this is only defined if fixed_rate returns true. Generally speaking, you don't need to override this.
Reimplemented in gr_test, gr_sync_block, gr_sync_decimator, and gr_sync_interpolator.
| virtual void gr_block::forecast | ( | int | noutput_items, |
| gr_vector_int & | ninput_items_required | ||
| ) | [virtual] |
Estimate input requirements given output request.
- Parameters:
-
noutput_items number of output items to produce ninput_items_required number of input items required on each input stream
Given a request to product noutput_items, estimate the number of data items required on each input stream. The estimate doesn't have to be exact, but should be close.
Reimplemented in gr_fractional_interpolator_cc, gr_fractional_interpolator_ff, gr_align_on_samplenumbers_ss, gr_clock_recovery_mm_cc, gr_clock_recovery_mm_ff, gr_mpsk_receiver_cc, gr_ofdm_sampler, gr_simple_framer, gr_stream_mux, gr_test, gr_sync_block, gr_sync_decimator, gr_sync_interpolator, atsc_bit_timing_loop, atsc_equalizer, atsc_field_sync_demux, atsc_field_sync_mux, atsc_pad, pager_flex_sync, trellis_siso_combined_f, and trellis_siso_f.
| virtual int gr_block::general_work | ( | int | noutput_items, |
| gr_vector_int & | ninput_items, | ||
| gr_vector_const_void_star & | input_items, | ||
| gr_vector_void_star & | output_items | ||
| ) | [pure virtual] |
compute output items from input items
- Parameters:
-
noutput_items number of output items to write on each output stream ninput_items number of input items available on each input stream input_items vector of pointers to the input items, one entry per input stream output_items vector of pointers to the output items, one entry per output stream
- Returns:
- number of items actually written to each output stream, or -1 on EOF. It is OK to return a value less than noutput_items. -1 <= return value <= noutput_items
general_work must call consume or consume_each to indicate how many items were consumed on each input stream.
Implemented in gr_fractional_interpolator_cc, gr_fractional_interpolator_ff, gr_pfb_arb_resampler_ccf, gr_pfb_channelizer_ccf, gr_pfb_clock_sync_ccf, gr_pfb_clock_sync_fff, gr_align_on_samplenumbers_ss, gr_clock_recovery_mm_cc, gr_clock_recovery_mm_ff, gr_copy, gr_keep_one_in_n, gr_mpsk_receiver_cc, gr_nop, gr_ofdm_bpsk_demapper, gr_ofdm_frame_acquisition, gr_ofdm_insert_preamble, gr_ofdm_sampler, gr_simple_correlator, gr_simple_framer, gr_skiphead, gr_squelch_base_cc, gr_squelch_base_ff, gr_stream_mux, gr_test, gr_sync_block, gr_sync_decimator, gr_sync_interpolator, atsc_bit_timing_loop, atsc_field_sync_demux, howto_square_ff, noaa_hrpt_deframer, pager_flex_sync, qtgui_sink_c, qtgui_sink_f, trellis_siso_combined_f, and trellis_siso_f.
| unsigned gr_block::history | ( | ) | const [inline] |
Assume block computes y_i = f(x_i, x_i-1, x_i-2, x_i-3...) History is the number of x_i's that are examined to produce one y_i. This comes in handy for FIR filters, where we use history to ensure that our input contains the appropriate "history" for the filter. History should be equal to the number of filter taps.
Referenced by gr_delay::delay(), gr_test::forecast(), and set_history().
| int gr_block::output_multiple | ( | ) | const [inline] |
| void gr_block::produce | ( | int | which_output, |
| int | how_many_items | ||
| ) |
Tell the scheduler how_many_items were produced on output stream which_output.
If the block's general_work method calls produce, general_work must return WORK_CALLED_PRODUCE.
| double gr_block::relative_rate | ( | ) | const [inline] |
return the approximate output rate / input rate
Referenced by gr_test::fixed_rate_ninput_to_noutput(), gr_test::fixed_rate_noutput_to_ninput(), and gr_test::forecast().
| void gr_block::set_detail | ( | gr_block_detail_sptr | detail | ) | [inline] |
References detail().
| void gr_block::set_fixed_rate | ( | bool | fixed_rate | ) | [inline, protected] |
References fixed_rate().
Referenced by gr_test::set_fixed_rate_public().
| void gr_block::set_history | ( | unsigned | history | ) | [inline] |
References history().
Referenced by gr_delay::set_delay().
| void gr_block::set_output_multiple | ( | int | multiple | ) |
Constrain the noutput_items argument passed to forecast and general_work.
set_output_multiple causes the scheduler to ensure that the noutput_items argument passed to forecast and general_work will be an integer multiple of
- Parameters:
-
multiple The default value of output multiple is 1.
Referenced by gr_sync_interpolator::set_interpolation().
| void gr_block::set_relative_rate | ( | double | relative_rate | ) |
Set the approximate output rate / input rate.
Provide a hint to the buffer allocator and scheduler. The default relative_rate is 1.0
decimators have relative_rates < 1.0 interpolators have relative_rates > 1.0
Referenced by gr_sync_decimator::set_decimation(), and gr_sync_interpolator::set_interpolation().
| virtual bool gr_block::start | ( | ) | [virtual] |
Called to enable drivers, etc for i/o devices.
This allows a block to enable an associated driver to begin transfering data just before we start to execute the scheduler. The end result is that this reduces latency in the pipeline when dealing with audio devices, usrps, etc.
Reimplemented in audio_osx_sink, audio_osx_source, msdd_rs_source_simple, msdd_source_simple, usrp_sink_base, usrp_source_base, usrp2_base, and usrp2_source_base.
| virtual bool gr_block::stop | ( | ) | [virtual] |
Called to disable drivers, etc for i/o devices.
Reimplemented in audio_osx_sink, audio_osx_source, msdd_rs_source_simple, msdd_source_simple, usrp_sink_base, usrp_source_base, usrp2_base, and usrp2_source_base.
The documentation for this class was generated from the following file:
